Process for removing harmful hydrocarbons, particularly plant protective aerosols and vapors, from the fresh air supplied to a vehicle cabin

ABSTRACT

The present invention relates to a process for removing harmful hydrocarbons, particularly plant protective aerosols and vapors, from the fresh air supplied to a vehicle cabin. The loaded fresh air is subjected to a partial condensation with subsequent phase separation. The fresh air is cooled below the dew point of the components to be removed in a type of cold trap. It has a device for collecting and draining the obtained condensate. A standard cooling plant may be installed for providing the cold necessary for partial condensation. If the vehicle is already equipped with an air conditioning system, then the cooling necessary for partial condensation is tapped directly from the air conditioner cycle. It is possible for the fresh air stream to be passed over the evaporator of the air conditioner. The cold air stream present following the removal of the condensate can be warmed in heat exchange with fresh air which is to be cooled prior to its further release into the vehicle cabin. This prevents an overcooling of the vehicle cabin.

BACKGROUND OF THE INVENTION

The invention relates to a process for removing harmful hydrocarbons,particularly plant protective aerosols and vapors, from the fresh airsupplied to a vehicle cabin.

Modern tractors used currently in agriculture have, in most cases, aclosed vehicle cabin. These vehicle cabins are constructed in asound-insulating manner and usually are already connected to an airconditioning system.

Especially when plant protectives, usually pesticides or herbicides,such as atrazine, bromacil or propazine, are sprayed, it isdisadvantageous that aerosols or vapors of such plant protectives arepassed along into the vehicle cabin together with the fresh air thatflows in and thus may have a negative or harmful effect on the health ofthe vehicle operator, particularly during a longer spraying operation.

It has already been suggested that air loaded with harmful hydrocarbonsin smaller work spaces, e.g. cabins or work places, etc., be cleanedwith active carbon filters. But the disadvantage of the use of suchfilters is, however, that the cleaning effect decreases greatly with anincreasing load, and the complete removal of the hazardous toxicsubstances is no longer ensured. In addition, the disposal of the loadedactive carbon filters themselves also poses problems.

SUMMARY OF THE INVENTION

The invention is based on the task of developing a simple and economicalprocess for removing harmful hydrocarbons, particularly plant protectiveaerosols and vapors, from the fresh air supplied to a vehicle cabin.

According to the invention, this task is solved in that the loaded freshair is subjected to a partial condensation with subsequent phaseseparation.

The process according to the invention makes it possible, in a simplemanner and without generating loaded waste substances, to remove theharmful hydrocarbons from the fresh air stream of the vehicle cabin. Itis only necessary to construct a type of cold trap in which the freshair is cooled below the dew point of the components to be removed andwhich possesses a device for collecting and draining the obtainedcondensate. A standard cooling plant may be installed for providing thecold necessary for partial condensation.

According to another characteristic of the invention, if the vehicle isalready equipped with an air conditioning system, it is found to be veryadvantageous that the cold necessary for partial condensation is coupleddirectly from the air conditioner cycle. It is e.g. possible that thefresh air stream is simply passed over the evaporator of the airconditioner.

Depending on the individually necessary degree of cooling of the freshair, it may be economically sensible according to another characteristicof the invention that, in order to avoid cooling losses, the cold airstream present following the removal of the condensate is prior to itsfurther conduit into the vehicle cabin warmed in heat exchange withfresh air which is to be cooled. This would also prevent an overcoolingof the vehicle cabin.

It was found that the process of the invention is particularlyadvantageous in connection with a gas washing level which precedes thepartial condensation and phase separation and is operated with water asa washing medium which may be taken e.g. from the fresh water tank ofthe plant protective spraying system. In the gas washing level, a largepart of the entrained plant protective aerosols and vapors is alreadyremoved from the fresh air stream, so that the following, furthertreatment level is accordingly relieved. In addition, the entrainedwater vapor from the gas washing level causes water drops to form duringthe partial condensation, into which water drops the harmful plantprotective particles are absorbed, so that the effectiveness of theremoval is increased even more.

Further explanations regarding the invention are found in the embodimentwhich is shown schematically in the figure.

BRIEF DESCRIPTION OF THE DRAWING

The figure shows a tractor used for spraying plant protectives.

DETAILED DESCRIPTION OF THE DRAWING

The figure shows a tractor 1 used for spraying plant protectives andhaving a vehicle cabin 2 which is supplied via a conduit 3 with cleanedfresh air. For cleaning, the fresh air which flows in via conduit 4 andis loaded with plant protective aerosols and vapors is first intimatelymixed in a high performance gas washing level 5 with washing watersupplied via a conduit 7 from a fresh water tank 6, whereby a large partof the harmful aerosols and vapors is already absorbed intocorresponding water drops. By exploiting the different inertias of gasand condensate, the phases are then separated again inside the highperformance gas washing level.

The fresh air is further cleaned in a second cleaning level 8 which isconstructed as a so-called cold trap. Here the air enriched withresidual amounts of aerosols and vapors as well as water vapor is firstpartially condensed by adding cold, and then undergoes phase separation.The condensate containing the harmful substances is collected, e.g. inthe bottom of a separating container, and is passed via a conduit 9together with the condensate from the gas washing level 5 which flows invia a conduit 10 into a container 11 for the plant protective solutionto be sprayed.

If necessary, e.g. because of safety reasons, the clean fresh airleaving the cleaning level 8 may still be passed over a so-called safetyfilter 13 prior to being supplied to the vehicle cabin.

A hygrometer 12 registers the residual moisture content of the cleanedair. A large increase in the moisture content may e.g. indicatemalfunctions in the system which could be caused by a breaking throughof the drops in the gas washing level 5 or too low of a cold supply inthe cleaning level 8.

I claim:
 1. A process for removing harmful substances from ambient airsupplied to a vehicle cabin, comprising the steps of:supplying ambientair to a first level connected to the vehicle cabin; subjecting theambient air supplied to the first level to a partial condensation toform condensates of the harmful substances; separating the condensatesfrom the ambient air by phase separation to form cooled clean air;removing the condensates via a conduit; and supplying the clean air tothe vehicle cabin.
 2. The process of claim 1, wherein the subjecting topartial condensation comprises effecting a heat exchange by coupling theambient air with cold air from an air conditioner cycle provided in thevehicle cabin.
 3. The process of claim 1, further comprising warming thecooled clean air by indirect heat exchange with the ambient air to bepartially condensed.
 4. The process of claim 1, further comprisingwashing the loaded ambient air in a gas washing level operated withwater prior to the partial condensation.
 5. The process of claim 1,further comprising supplying the condensates to a container.
 6. Theprocess of claim 1, further comprising passing the clean air over asolid filter prior to supplying the clean air to the vehicle cabin. 7.The process of claim 1, further comprising passing the clean air over amoisture sensor prior to supplying the clean air to the vehicle cabin.8. A process for removing harmful substances from ambient air suppliedto a vehicle cabin, comprising the steps of:supplying ambient air to afirst level; subjecting the ambient air supplied to the first level to afirst partial condensation to form first condensates of harmfulsubstances; separating the first condensates from the ambient air by afinest phase separation to form cooled clean air; removing the firstcondensates via a first conduit; supplying the cooled clean air to asecond cleaning level; effecting a second partial condensation of thecooled clean air to form second condensates of any residual harmfulsubstances; separating the second condensates from the cooled clean airby phase separation to form clean air; removing the second condensatesvia a second conduit; and supplying the clean air to the vehicle.
 9. Theprocess of claim 8, wherein the subjecting to first partial condensationcomprises effecting a heat exchange by coupling the ambient air withcold air from an air conditioner cycle provided in the vehicle cabin.10. The process of claim 8, further comprising warming the cooled cleanair by indirect heat exchange with the ambient air to be partiallycondensed.
 11. The process of claim 8, further comprising washing theambient air in a gas washing level operated with water prior to thefirst partial condensation.
 12. The process of claim 8, furthercomprising supplying the first and second condensates to a container.13. The process of claim 8, further comprising passing the clean airover a solid filter prior to supplying the clean air to the vehiclecabin.
 14. The process of claim 8, further comprising passing the cleanair over a moisture sensor prior to supplying the clean air to thevehicle cabin.